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Kivy: Updating Label in several widgets and screens

I'm trying to update the value of a label in 2 widgets and a screen. This should be pretty straightforward but I haven't been able to make it work!
I suspect that whatever I'm doing is not being picked up by the GUI for some reason. I say this because when "printing values" to debug the value does update as expected.
Finally, I've looked at several solutions but neither seem to work: Kivy Label Text does not update, Kivy: Label text does not update during for-loop, Kivy Label.text Property doesn't update on the UI
The screen I'm trying to update:
Screens/recipe_screen.py
from kivymd.uix.screen import MDScreen
class RecipeScreen(MDScreen):
pass
Screens/recipe_screen.kv
#:import CounterWidget Components.counter_widget.CounterWidget
#:import IngredientsLabel Components.ingredients_label.IngredientsLabel
<RecipeScreen>:
name: 'recipe_screen'
id: recipe_screen
MDBoxLayout:
adaptive_height: True
orientation: 'horizontal'
padding: 30, 20
spacing: 0
IngredientsLabel:
id: il
label_text: 'text I'm trying to update'
CounterWidget:
Widget 1: this is what I'm calling from the GUI
components/counter_widget.py
from kivymd.uix.card import MDCard
from Components.ingredients_label import IngredientsLabel
class CounterWidget(MDCard):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.counter = 4
def increase_widget(self):
self.counter += 1
self.ids['counter_text'].text = str(self.counter) <--- THIS WORKS FINE
ingredient_label_ref = IngredientsLabel
ingredient_label_ref().change_label(self.counter) <--- THIS DOES NOT WORK
components/counter_widget.kv
#:import RecipeScreen Screens.recipe_screen.RecipeScreen
<CounterWidget>:
elevation: 5
border_radius: 15
radius: [15]
size_hint: None, None
size: 250, 90
MDGridLayout:
MDLabel:
id: counter_text
text: '4'
Widget 2: this is the widget I'm trying to update based on Widget 1
components/ingredients_label.py
from kivymd.uix.boxlayout import MDBoxLayout
class IngredientsLabel(MDBoxLayout):
def change_label(self, counter):
self.ids['servings_counter'].text = str(counter) + ' servings' <--- DOES NOT UPDATE GUI
print('IngredientsLabel: ' + str(counter) + ' servings') <--- PRINTS CORRECTLY IN TERMINAL
components/ingredients_label.kv
#:import RecipeScreen Screens.recipe_screen.RecipeScreen
<IngredientsLabel>:
adaptive_height: True
orientation: 'vertical'
MDLabel:
id: servings_counter
markup: True
text: '4 servings'
font_style: 'Subtitle2'
main.py
from kivy.core.window import Window
from kivymd.app import MDApp
from kivy.factory import Factory
from kivy.uix.screenmanager import ScreenManager
from Screens.recipe_screen import RecipeScreen
from Screens.carousel_screen import CarouselScreen
class MainApp(App, MDApp):
def build_app(self):
Window.size = [350, 560]
sm = ScreenManager()
sm.add_widget(RecipeScreen(name='recipe_screen'))
sm.add_widget(CarouselScreen(name='carousel_screen'))
return sm
if __name__ == '__main__':
MainApp().run()
Update post #John Anderson suggestion to:
def increase_widget(self):
self.counter += 1
self.ids['counter_text'].text = str(self.counter)
ingredient_label_ref = MDApp.get_running_app().root.get_screen('recipe_screen').ids.il # get reference to IngredientsLabel
ingredient_label_ref.change_label(self.counter)
Unfortunately, this didn't work either.
I also tried referencing in the .kv file via:
Changing the components/ingredients_label.kv to
#:import RecipeScreen Screens.recipe_screen.RecipeScreen
<IngredientsLabel>:
adaptive_height: True
orientation: 'vertical'
label_text: 'None'
MDLabel:
markup: True
text:'Ingredients for'
font_style: 'H6'
MDLabel:
markup: True
text: root.label_text
font_style: 'Subtitle2'
and components/counter_widget.py to (while keeping the 'il' id reference for the IngredientsLabel widget on the RecipeScreen)
from kivymd.uix.card import MDCard
from Components.ingredients_label import IngredientsLabel
class CounterWidget(MDCard):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.counter = 4
def increase_widget(self):
self.counter += 1
self.ids['il'].label_text = str(self.counter)
but this didn't work either (no error, but no update to the UI either...).
I included the App class above as well.

Without a complete runnable code (you have not provided an App class), it is difficult to provide a definitive answer. However, assuming that your App creates a ScreenManager with RecipeScreen as one of its Screens, you can modify your increase_widget() method:
def increase_widget(self):
self.counter += 1
self.ids['counter_text'].text = str(self.counter)
ingredient_label_ref = MDApp.get_running_app().root.get_screen('recipe_screen').ids.il # get reference to IngredientsLabel
ingredient_label_ref.change_label(self.counter)
In order for this to work, you must add some ids to your kv:
<RecipeScreen>:
name: 'recipe_screen'
id: recipe_screen
MDBoxLayout:
adaptive_height: True
orientation: 'horizontal'
padding: 30, 20
spacing: 0
IngredientsLabel:
id: il # added id
CounterWidget:
id: cw # added, but not required

How to refresh GridLayout in Kivy with kv file

I need help.
I created a small mobile application with Kivy.
I have two screens: ScreenList and ScreenDetail.
However the screen(ScreenList) containing GridLayout does not refresh
ScreenList: contains a list of items
ScreenDetail: Contains the details of a single item.
How the app works:
When I click on the first item on button 1
I go to the details of the item.
I modify the second field. I replace the text: Firt element for First and update data
After recording, I redirect the application to the screens which contain (ScreenList) the list of elements.
But the list of elements remains unchanged then the data has been modified in the database.
6.And when I return to the screen (ScreenDetail) which contains the details, there I see that the data is updated.
How can I refresh the item list in ScreenList?
Here are the pictures as an example
List before update
before update
after update
List after update
Here is the python code:
import kivy
from kivy.app import App
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.gridlayout import GridLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.scrollview import ScrollView
from kivy.properties import ObjectProperty, StringProperty
from kivy.lang import Builder
from kivymd.uix.picker import MDTimePicker
from kivymd.uix.picker import MDDatePicker
from kivymd.app import MDApp
import sqlite3
import os.path
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
db_path = os.path.join(BASE_DIR, "donnee/ProjetMaison.db")
def donnee_dic(cursor, row):
d = {}
for idx, col in enumerate(cursor.description):
d[col[0]] = row[idx]
return d
cur_id = None
class ScreenList(Screen):
data_grid = ObjectProperty()
def go_to_detail(self, instance):
global cur_id
cur_id = int(instance.text)
self.manager.current = 'screen_detail'
def __init__(self, **kwargs):
super(ScreenList, self).__init__(**kwargs)
con_list_course = sqlite3.connect(db_path)
con_list_course.row_factory = donnee_dic
curss_list_course = con_list_course.cursor()
data_list_course = curss_list_course.execute("select * FROM courses")
self.data_grid.bind(minimum_height=self.data_grid.setter('height'))
for row in data_list_course:
template_screen = GridLayout(cols=2, size_hint_y=None, height=40)
template_screen.add_widget(Label(text=row['nom']))
template_screen.add_widget(Button(text=str(row['id']), on_press=self.go_to_detail))
self.data_grid.add_widget(template_screen)
con_list_course.close()
def Maj_colonne(id, nom):
try:
sqliteConnection = sqlite3.connect(db_path)
cursor = sqliteConnection.cursor()
sqlite_update_query = """Update courses set nom = ? where id = ?"""
columnValues = (nom, id)
cursor.execute(sqlite_update_query, columnValues)
sqliteConnection.commit()
sqliteConnection.commit()
cursor.close()
except sqlite3.Error as error:
print("Erreur de connexion", error)
finally:
if sqliteConnection:
sqliteConnection.close()
class ScreenDetail(Screen):
label_id = ObjectProperty()
label_nom = ObjectProperty()
def __init__(self, **kwargs):
super(ScreenDetail, self).__init__(**kwargs)
def on_enter(self):
global cur_id
conn = sqlite3.connect(db_path)
cursor = conn.execute("select * FROM courses where id=?",str(cur_id))
for row in cursor:
self.label_id.text = str(row[0])
self.label_nom.text = str(row[1])
cursor.close()
def update_course(self):
id_pk = self.ids['label_id'].text
nom = self.ids['label_nom'].text
if id_pk:
Maj_colonne(str(id_pk), str(nom))
self.ids['label_id'].text = ''
self.ids['label_nom'].text = ''
self.manager.current = 'screen_list'
class Listapp(MDApp):
def build(self):
screenmanager = ScreenManager()
screenmanager.add_widget(ScreenList(name='screen_list'))
screenmanager.add_widget(ScreenDetail(name='screen_detail'))
return screenmanager
if __name__ == '__main__':
Listapp().run()
Here is the kv code:
#:import utils kivy.utils
<ScreenList>:
data_grid: data_grid
MDBoxLayout:
orientation: 'vertical'
md_bg_color: app.theme_cls.primary_color
radius: [25, 0, 0, 0]
ScrollView:
MDGridLayout:
id: data_grid
cols: 1
spacing:10
size_hint_y:None
<ScreenDetail>:
label_id: label_id
label_nom: label_nom
MDBoxLayout:
orientation: 'vertical'
md_bg_color: app.theme_cls.primary_color
ScrollView:
GridLayout:
id: detail_grid
cols:2
Label:
text: 'Numéro:'
bold: True
TextInput:
id: label_id
text: ''
Label:
text: 'Nom:'
bold: True
TextInput:
id: label_nom
text: ''
Button:
text: 'OK'
size_hint_y: None
on_press: root.update_course()
Thank you

Few notes to take, in general, when working with Kivy
When you're trying to share data in between screens, it's often useful to use app methods instead of specific methods of screens.
And when you need to create lots of buttons, maybe inside a loop, and bind methods on its events( on_press, on_release), it's often bad to create button instances on the fly and bind methods on its events because you'll need to do extra work to make sure that those bound methods are called with right parameters when events are fired. Rather create a custom class template and use that instead.
Working solution for your problem (only showing sections that has been added/updated
Created custom GridLayout:
class MyGrid(GridLayout):
pass
Updated __init__ method inside ScreenList:
def __init__(self, **kwargs):
#...
app = MDApp.get_running_app()
for row in data_list_course:
template_screen = MyGrid()
template_screen.ids.lbl.text = row['nom']
template_screen.ids.btn.text = str(row['id'])
self.data_grid.add_widget(template_screen)
Added methods inside app class:
class Listapp(MDApp):
def build(self):
self.screenmanager = ScreenManager()
self.screenmanager.add_widget(ScreenList(name='screen_list'))
self.screenmanager.add_widget(ScreenDetail(name='screen_detail'))
return self.screenmanager
def go_to_detail_(self, inst):
self.inst = inst
self.screenmanager.current = 'screen_detail'
def update_course_(self, label_id, label_nom):
c = self.inst.children[::-1]
c[0].text = label_nom.text
c[1].text = label_id.text
print(label_id.text, label_nom.text)
if label_id.text:
Maj_colonne(str(id_pk), str(nom))
label_nom.text = ''
label_id.text = ''
self.screenmanager.current = 'screen_list'
Here's the updated kv code:
#:import utils kivy.utils
<ScreenList>:
data_grid: data_grid
MDBoxLayout:
orientation: 'vertical'
md_bg_color: app.theme_cls.primary_color
radius: [25, 0, 0, 0]
ScrollView:
MDGridLayout:
id: data_grid
cols: 1
spacing:10
size_hint_y:None
<ScreenDetail>:
label_id: label_id
label_nom: label_nom
MDBoxLayout:
orientation: 'vertical'
md_bg_color: app.theme_cls.primary_color
ScrollView:
GridLayout:
id: detail_grid
cols:2
Label:
text: 'Numéro:'
bold: True
TextInput:
id: label_id
text: ''
Label:
text: 'Nom:'
bold: True
TextInput:
id: label_nom
text: ''
Button:
text: 'OK'
size_hint_y: None
on_press: app.update_course_(label_id, label_nom)
<MyGrid>:
cols:2
size_hint_y:None
height:40
Label:
id: lbl
text: ''
Button:
id: btn
text: ''
on_press:
app.go_to_detail_(root)

Kivy - Calling a pulsing method from one class to another

I have the following classes in my kivy app, and i would like to call the blink method in my mainApp class. The start pulsing and blink methods enable the MainWindow background to pulse. However it's not working inside the MainWindow class and i need to call it in my mainApp class. Commented out (build method in mainApp) is what i tried, which results to the error Exception: Invalid instance in App.root. My python file:
from kivy.uix.widget import Widget
from kivy.properties import ObjectProperty
from kivy.lang import Builder
from kivy.uix.screenmanager import Screen
from kivy.core.window import Window
from kivymd.app import MDApp
from kivy.uix.image import Image
from kivy.animation import Animation
from kivy.clock import Clock
from kivy.properties import ColorProperty
from kivy.uix.popup import Popup
from kivy.uix.floatlayout import FloatLayout
from plyer import filechooser
data = ""
class MainWindow(Screen):
def analyze_data(self):
global data
data = self.ids.user_input.text
data = analyze(data)
animated_color = ColorProperty()
pulse_interval = 4
def blink(self):
x = Clock.schedule_once(self.start_pulsing, 5)
return x
def start_pulsing(self, *args):
d = self.pulse_interval / 2
anim = Animation(animated_color=(69/255, 114/255, 147/255, 1), duration=d) + Animation(animated_color=(1, 1, 1, 1), duration=d)
anim.repeat = True
anim.start(self)
class OutputScreen(Screen):
def on_enter(self, *args):
self.ids.output_label.text = data
class mainApp(MDApp):
def __init__(self):
super().__init__()
def choose_file(self):
try:
filechooser.open_file(on_selection = self.handle_selection)
except:
pass
def handle_selection(self,selection):
global path
selection_ls = selection[0]
path = selection_ls
#print(path)
def change_screen(self,screen):
screemanager = self.root.ids['screenmanager']
screemanager.current = screen
def change(self):
self.change_screen('output')
def back(self):
self.change_screen('main')
'''
def build(self):
x = MainWindow().blink()
return x'''
and my kv file:
#:import utils kivy.utils
GridLayout:
cols:1
ScreenManager:
id: screenmanager
MainWindow:
id: main
name: 'main'
OutputScreen:
id: output
name: 'output'
<MainWindow>:
BoxLayout:
orientation:'vertical'
MDBottomNavigation:
panel_color: utils.get_color_from_hex("#ffffff")
MDBottomNavigationItem:
name:'analytics'
text:'analytics'
icon:'account-circle'
FloatLayout:
size: root.width, root.height
canvas.before:
Color:
rgba: root.animated_color
Rectangle:
pos:self.pos
size:self.size
TextInput:
multiline:True
id: user_input1
pos_hint:{"x" : 0.05, "top" : 0.9}
size_hint: 0.9, 0.37
Label:
markup: True
id:input_label
pos_hint:{"x" : 0, "top":1}
size_hint: 1 ,0.08
font_size : 32
bold: True
canvas.before:
Color:
rgb: utils.get_color_from_hex("01121c")
Rectangle:
size: self.size
pos: self.pos
Button:
pos_hint:{"top" : 0.51, "x" : 0.05}
size_hint: (None,None)
width : 150
height : 40
font_size : 23
text:'Submit'
on_press: root.analyze_data()
on_release: app.change()
Button:
pos_hint:{"top":0.42, "x":0.05}
size_hint: (None,None)
width : 150
height : 40
font_size : 23
text:'Upload'
on_release:app.choose_file()
Button:
id:'info_button'
pos_hint:{"top":0.47, "x":0.8}
size_hint: (None,None)
width : 50
height : 22
font_size : 23
text:'i'
on_release:root.analytics_info()
<OutputScreen>:
ScrollView:
GridLayout:
cols:1
MDIconButton:
icon:'arrow-left'
pos_hint:{'top':1,'left':1}
size_hint: 0.1,0.1
user_font_size : '64sp'
on_release: app.back()
Label:
id: output_label
multiline:True
text_size: self.width, None
size_hint: 1, None
height: self.texture_size[1]
color: 0,0,0,1
padding_x: 15
Any help will be much appreciated.

The build() method of an App should return a Widget that will become the root of the App. But your build() method returns a ClockEvent (the return from Clock.schedule_once()). Try changing your build() method to:
def build(self):
x = MainWindow()
x.blink()
return x
Since you do not call Builder.load_file(), I assume that your kv file is named main.kv, and therefore will get loaded automatically. If that is true, then you do not need a build() method at all. Instead add an on_start() method to your mainApp class, like this:
def on_start(self):
self.root.ids.main.blink()

Kivy: How to add widgets dinamically in kv, and how to refer to them from py script?

In a previous question, I asked how to have a row of text inputs which is dinamically added on press of a button, all from a py script.
I am now attempting at moving all my layout code to a kv file. While this was pretty straightforward for the widgets which appear on screen by default, I am not really sure of how to define the dinamically added text inputs from the kv file.
My solution, at present, is to create the 'default' widgets in the kv file, and to add the other ones from the py script through the addIngredient method. Below a minimal working version.
The kv file:
WMan:
AddWindow:
<AddWindow>:
name: 'add'
ingsGrid: ingsGrid
ing1: ing1
quant1: quant1
addIng: addIng
saveButton: saveButton
StackLayout:
id: ingsGrid
size_hint: .9, None
height: self.minimum_height
orientation: 'lr-tb'
spacing: '5sp', '5sp'
TextInput:
id: ing1
multiline: False
size_hint: .65, None
height: self.minimum_height
TextInput:
id: quant1
multiline: False
size_hint: .25, None
height: self.minimum_height
Button:
id: addIng
text: "+"
size_hint: .1, None
height: ing1.height
on_release: root.addIngredient(self)
Button:
id: saveButton
text: "Save"
size_hint: .3, None
on_release:
root.saveRec(self)
The py script reads:
from kivy.app import App
from kivy.properties import ObjectProperty
from kivy.uix.button import Button
from kivy.uix.textinput import TextInput
from kivy.uix.stacklayout import StackLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
class AddWindow(Screen):
def __init__(self, **kwargs):
super(AddWindow, self).__init__(**kwargs)
recipeName = ObjectProperty(None)
ingsGrid = ObjectProperty(None)
ing1 = ObjectProperty(None)
quant1 = ObjectProperty(None)
self.i = 1
self.ingsList = {}
self.ingsList[0] = ing1
self.quants = {}
self.quants[0] = quant1
def addIngredient(self, instance):
tmp_children_list = self.ingsGrid.children[:]
self.ingsGrid.clear_widgets()
# range(start,stop[, step])
for index in range(len(tmp_children_list)-1, -1, -1):
# the last item, then last-1, etc
child = tmp_children_list[index]
# add the last first (new ones will be added on top)
self.ingsGrid.add_widget(child)
# if child is the pressed button
if child == instance:
self.ing = TextInput(
size_hint=(.65, None),
height='30sp')
self.ingsGrid.add_widget(self.ing)
self.ingsList[self.i] = self.ing
self.quant = TextInput(
size_hint=(0.25, None),
height='30sp')
self.ingsGrid.add_widget(self.quant)
self.quants[self.i] = self.quant
self.i += 1
self.addNext = Button(
text="+",
size_hint=(0.1, None),
height='30sp')
self.addNext.bind(on_press=self.addIngredient)
self.ingsGrid.add_widget(self.addNext)
def saveRec(self, instance): # grab all inputs and send to SQLite db
print(self.ingsList)
print(self.ingsList[0].text)
print(self.ingsList[1].text)
class WMan(ScreenManager):
pass
kv = Builder.load_file("test.kv")
class TestApp(App):
def build(self):
return kv
if __name__ == "__main__":
TestApp().run()
My problem here is twofold: first, while this way of dinamically adding rows works as it should, it is to me a bit messy to have half of the layout defined on the kv file, and the other half defined in the py script. So my first question is:
1. Is there a way to move the entire layout to the kv file?
Second questions is:
2. How do I access the content of textInput 'ing1' (the one created in the kv file)?
when I run print(self.ingsList), I get:
{0: <ObjectProperty name=>, 1: <kivy.uix.textinput.TextInput object at 0x000002077FB89C88>}
So while I can easily do print(self.ingsList[1].text), running print(self.ingsList[0].text) will give error:
AttributeError: 'kivy.properties.ObjectProperty' object has no attribute 'text'

Here is a modified version of your code that does what I think you want:
from kivy.app import App
from kivy.properties import ObjectProperty, NumericProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
class AddWindow(Screen):
def __init__(self, **kwargs):
super(AddWindow, self).__init__(**kwargs)
recipeName = ObjectProperty(None)
ingsGrid = ObjectProperty(None)
ing1 = ObjectProperty(None)
quant1 = ObjectProperty(None)
self.i = 1
self.ingsList = {}
self.ingsList[0] = ing1
self.quants = {}
self.quants[0] = quant1
def saveRec(self, instance): # grab all inputs and send to SQLite db
for child in self.ids.ingsGrid.children:
if isinstance(child, OneRow):
print('ingedient name:', child.ids.ing1.text)
print('quantity:', child.ids.quant1.text)
print('')
class WMan(ScreenManager):
pass
class OneRow(BoxLayout):
inst_count = NumericProperty(0)
count = 0
def __init__(self, **kwargs):
OneRow.count += 1
self.inst_count = OneRow.count
super(OneRow, self).__init__(**kwargs)
def get_index(self):
par = self.parent
if par is None:
return None
index = 0
for index in range(len(par.children) - 1, -1, -1):
child = par.children[index]
if child == self:
return index
kv_str = '''
#:import Factory kivy.factory.Factory
WMan:
AddWindow:
id: add
#:set row_height 30
<OneRow>:
orientation: 'horizontal'
size_hint_y: None
height: row_height
TextInput:
id: ing1
multiline: False
size_hint: .65, None
height: row_height
TextInput:
id: quant1
multiline: False
text: str(root.inst_count)
size_hint: .25, None
height: row_height
Button:
id: addIng
text: "+"
size_hint: .1, None
height: row_height
on_release: app.root.ids.add.ids.ingsGrid.add_widget(Factory.OneRow(), index=root.get_index())
<AddWindow>:
name: 'add'
ingsGrid: ingsGrid
saveButton: saveButton
StackLayout:
id: ingsGrid
size_hint: .9, None
height: self.minimum_height
orientation: 'lr-tb'
spacing: '5sp', '5sp'
OneRow:
Button:
id: saveButton
text: "Save"
size_hint: .3, None
on_release:
root.saveRec(self)
'''
# kv = Builder.load_file("test.kv")
kv = Builder.load_string(kv_str)
class TestApp(App):
def build(self):
return kv
if __name__ == "__main__":
TestApp().run()
I used Builder.load_string() instead of load_file() just for my own convenience.
I have created a class named OneRow that holds a single row from the ingredients list, and the + Button now just adds an instance of that class. The get_index() method of that class is only used to position new ingredients below the row with the Button that was pressed. And the other code in that class is just to add some identifying info. If those things are not important to you, you can eliminate the OneRow class definition from the python, and just replace <OneRow>: in the kv with <OneRow#BoxLayout>: and where the OneRow is added you can just set index=1.

Overlapping of custom Widget in ScrollView GridLayout in Kivy

this is a trial code that I want to implement in my final project.
Python Code:
import kivy
kivy.require('1.0.6')
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
class Wid(BoxLayout):
def settxt(self,i):
lab = self.ids['lab']
but = self.ids['but']
lab.text = "Label Number {}".format(i)
but.text = "Button Number {}".format(i)
class Win1(Screen):
i=0
def addw(self):
box1 = self.ids['box1']
self.i = self.i +1
w = Wid()
w.settxt(self.i)
box1.add_widget(w)
def switch(self):
sm.current="win2"
class Win2(Screen):
def switch(self):
sm.current="win1"
class WindowManager(ScreenManager):
pass
kv = Builder.load_file("test.kv")
sm = WindowManager()
screens = [Win1(name="win1"), Win2(name="win2")]
for screen in screens:
sm.add_widget(screen)
sm.current = "win1"
class Test(App):
def build(self):
return sm
if __name__ == '__main__':
Test().run()
Kivy Code:
<Wid>:
lab:lab
but:but
BoxLayout:
height: self.minimum_height
size: root.size
Label:
id: lab
Button:
id: but
<Win1>
name:"win1"
box1:box1
BoxLayout:
height: self.minimum_height
orientation: "vertical"
BoxLayout:
size_hint: 1,0.2
Button:
text:"window 2"
on_release:
root.switch()
Button:
text:"add wid"
on_release:
root.addw()
ScrollView:
GridLayout:
id:box1
orientation: "vertical"
spacing: 2
size_hint_y: None
height: self.minimum_height
row_default_height: 60
cols:1
<Win2>
name: "win2"
BoxLayout:
id: bl
height: bl.minimum_height
size_hint_y: None
Button:
text:"window 2"
on_release:
root.switch()
With the press of the switch, I expect that my custom widget to get in the gridlayout in the scrollview, one below the other. But instead, each new widget appears in the last cell of the layout and overlaps on the previous one and empty cells keep on forming above them.
Don't know where it's going wrong.

Here I have moved the kv to a separate file, and dynamically created the screens.
Key points: I add the screens dynamically in on_start, this is after the build has completed. I create the ScreenManager in kv, and use the id to add the screens. In the kv code I put the ScreenManger in a BoxLayout. This is a personal preference. I do this so when accessing objects the root widget is not the screen manager. Therefore in the switch() methods, the addressing uses the assigned id, rather than relying on the root widget being a screenmanager.
FWIW: If the switch code is only going to change screens I would move those single lines into KV.
import kivy
kivy.require('1.0.6')
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen
class Wid(BoxLayout): # Change to layout
def settxt(self, i):
lab = self.ids['lab']
but = self.ids['but']
lab.text = "Label Number {}".format(i)
but.text = "Button Number {}".format(i)
class Win1(Screen):
i = 0
def addw(self):
box1 = self.ids['box1']
self.i = self.i + 1
w = Wid()
w.settxt(self.i)
box1.add_widget(w)
#staticmethod
def switch():
app = App.get_running_app()
app.root.ids.sm.current = "win2"
class Win2(Screen):
#staticmethod
def switch():
app = App.get_running_app()
app.root.ids.sm.current = "win1"
class WidgetQ1App(App):
def build(self):
return Builder.load_file('widgetq.kv')
def on_start(self):
screens = [Win1(name="win1"), Win2(name="win2")]
sm = self.root.ids.sm
for screen in screens:
sm.add_widget(screen)
WidgetQ1App().run()
And the KV code:
<Wid>: # Put widgets in a layout, not a widget.
lab:lab
but:but
BoxLayout:
size: root.size
Label:
id: lab
Button:
id: but
<Win1>
# name:"win1"
box1:box1
BoxLayout:
orientation: "vertical"
BoxLayout:
size_hint: 1,0.2
Button:
text:"window 2"
on_release:
root.switch()
Button:
text:"add wid"
on_release:
root.addw()
ScrollView:
GridLayout:
id:box1
orientation: "vertical"
spacing: 2
size_hint_y: None
height: self.minimum_height
row_default_height: 60
cols:1
<Win2>:
# name: "win2"
BoxLayout:
Button:
text:"window 2"
on_release:
root.switch()
BoxLayout:
ScreenManager:
id: sm

<win2>
name: "win2"
size_hint_y: None
height: bl.minimum_height
BoxLayout:
id: bl
Button:
text:"window 2"
on_release:
root.switch()
Your custom widgets don't have a height defined, try changing to something like the above.
Also, start your class names with an upper case letter, kv requires this in some cases. For instance, win2 should be Win2.

A number of issues here, see the comments. The biggest problem I see is putting items in a widget. Put Widgets in a layout, not other widgets.
import kivy
kivy.require('1.0.6')
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen
from kivy.lang import Builder
kv = """
<Wid>: # Put widgets in a layout, not a widget.
lab:lab
but:but
BoxLayout:
size: root.size
Label:
id: lab
Button:
id: but
<Win1>
# name:"win1"
box1:box1
BoxLayout:
orientation: "vertical"
BoxLayout:
size_hint: 1,0.2
Button:
text:"window 2"
on_release:
root.switch()
Button:
text:"add wid"
on_release:
root.addw()
ScrollView:
GridLayout:
id:box1
orientation: "vertical"
spacing: 2
size_hint_y: None
height: self.minimum_height
row_default_height: 60
cols:1
<Win2>:
# name: "win2"
BoxLayout:
Button:
text:"window 2"
on_release:
root.switch()
ScreenManager:
id: sm
Win1:
name: 'win1'
Win2:
name: 'win2'
"""
class Wid(BoxLayout): # Change to layout
def settxt(self,i):
lab = self.ids['lab']
but = self.ids['but']
lab.text = "Label Number {}".format(i)
but.text = "Button Number {}".format(i)
class Win1(Screen):
i = 0
def addw(self):
box1 = self.ids['box1']
self.i = self.i + 1
w = Wid()
w.settxt(self.i)
box1.add_widget(w)
#staticmethod
def switch():
app = App.get_running_app()
app.root.current = "win2"
class Win2(Screen):
#staticmethod
def switch():
app = App.get_running_app()
app.root.current = "win1"
# class WindowManager(ScreenManager):
# pass
# kv = Builder.load_file("test.kv")
# sm = WindowManager()
#
# screens = [win1(name="win1"), win2(name="win2")]
# for screen in screens:
# sm.add_widget(screen)
#
# sm.current = "win1"
class WidgetQApp(App):
def build(self):
return Builder.load_string(kv)
WidgetQApp().run()